Ive felt depressed since high school but ive never addressed it but now as i am finishing up college people and my have noticed it more what do i do

Find a therapist: People are often not born with the skill set needed to handle some of life's encounters. You wouldn't try to set your broken leg by yourself & shouldn't try to deal with a depressed mood alone. An unrelated therapist that can help you explore the triggers to your feelings & how to get pas them is the next step. They may work with someone who would suggest some temporary meds while you do the work.